The present invention is directed generally to manually wound tape measures, and more particularly to manually wound tape measures with a tape grip element that is normally slidable along the tape but grips the tape when the tape is fully retracted.
Modern tape measures may be generally divided into two classesxe2x80x94power return tape measures and manually wound tape measures. The former class typically include a metallic tape blade of not more than forty feet in length and a spring-based mechanism that acts to retract the tape blade into the tape measure housing unless a tape lock is engaged. In contrast, the latter class typically use flexible fabric, fiberglass, and/or plastic tapes of fifty feet or more in length and do not include a powered return mechanism. Instead, the manually wound tape measures rely on some form of manually operated crank mechanism to rewind the tape into the tape measure housing. These manually wound tape measures are typically used for measuring long relatively distances, such as complete foundation walls, vehicle accident scenes, property lines, etc.
One problem with manually wound tape measures is preventing unintended play-out of the tape blade. For instance, when the manually wound tape measure is carried by a user over long distances, the manually wound tape measure typically swings back and forth at the end of the user""s arm. This swinging motion has the tendency to cause the tape to play out slightly, on the order of six to twelve inches. With this much tape played out, the end of the tape may whip back and forth, and may strike the user or snag on nearby objects. Both results are obviously undesirable. To counter this, many manually wound tape measures use a complex locking crank mechanism that acts to prevent play out of the tape when the crank is in the xe2x80x9clockxe2x80x9d position. While such locking crank mechanisms are somewhat effective, their effectiveness drops off significantly when the crank drive ratio (number of turns of tape take-up reel per turn of crank) is higher than 1:1. For instance, a manually wound tape measure with the approximately 3.75:1 drive ratio of the crank mechanism described in U.S. Pat. No. 4,813,625 is more likely to unintentionally play out tape than a traditional manually wound tape measure with 1:1 drive ratio retraction mechanism. Recognition of this problem has led to the use of even more complex drive/brake mechanisms, such as that disclosed in U.S. Pat. No. 6,134,801, with the necessarily accompanying higher manufacturing costs. As such, none of the prior art solutions have proven completely satisfactory.
Thus, there remains a need for alternative designs of manually wound tape measures that address the problem of unintended play out while remaining simple to manufacture.
One aspect of the present invention is directed to a manually wound tape measure that has a housing having a mouth portion. A flexible tape extends through the mouth portion, with the tape having an anchored end mated to the housing and a free end manually displaceable with respect thereto. A hook may be attached to this free end of the tape. A grip element is slidably mounted on the tape for movement relative thereto. The grip element includes an internal passage through which the tape extends and is resiliently deformable between an uncompressed state and a compressed state. Manually powered retraction of the tape into the housing causes the grip element to be urged into the mouth portion of the housing such that the grip element is, by interaction with the housing, deformed against and compressively grips the tape. For instance, the internal passage of the grip element may have a first cross-sectional size larger than the tape in the uncompressed state, and at least a portion of the passage may assume a second cross-sectional size smaller than the first cross-sectional size when the grip element is deformed against and compressively grips the tape. Preferably, the tape measure further includes a manually powered retraction mechanism having a drive ratio of greater than 1:1.
In some embodiments, the grip element may be made from a clear material, have a length of at least 1.25 inches, and/or have a hardness of about 50 to about 65 on the Shore A scale. Preferably, the exterior of the grip element is tapered. The grip element may have a central area larger in external cross-section than side portions thereof in the uncompressed state. Likewise, the grip element may include a plurality of external ridges, including a central ridge in the central area and side ridges in the side portions. The tape may optionally include a reinforcing strip applied over the free end of the tape, with the internal passage of the grip element sized to allow the reinforcing strip to slidably fit therein in the uncompressed state.
Another aspect of the invention is directed to a manually wound tape measure that is manually changeable from a deployed configuration wherein the free end of the tape is disposed remote from the housing, the grip element is in the uncompressed state, and the grip element is slidable along the tape to a retracted configuration wherein the tape is retracted, the grip element is at least partially disposed within the mouth, and the grip element is in the compressed state with the grip element deformed against and compressively gripping the tape. such a tape measure advantageously includes a manually operable crank mechanism operable to change the tape measure from the deployed configuration to the retracted configuration.
One method of operating a manually wound tape measure according to the present invention includes retracting a free end of a flexible measuring tape towards a housing via a manually powered retraction mechanism having a drive ratio of greater than 1:1; the housing having a mouth portion and the tape extending through a grip element resiliently deformable between an uncompressed state and a compressed state; sliding the tape through a passage in the grip element during the retracting; engaging the grip element by the mouth portion; compressing the grip element, by the housing, such that the grip element is deformed against and compressively grips the tape; and thereafter, holding the free end proximate the mouth via the grip element with the grip element in the compressed state. The process may continue with thereafter deploying the tape, the deploying comprising pulling the free end away from the housing and thereby causing the grip element to assume the uncompressed state, wherein the tape is slidable relative to the tape when the grip element is in the uncompressed state.
The present invention may include one or more of the aspects discussed above.